Devices and methods for sampling a beam in an optical path are available in a variety of configurations. Typically, optical devices such as beam splitters are used for beam sampling. Two common types of beam splitters include a plate beam splitter (as shown in FIG. 1) and a cube beam splitter (as shown in FIG. 2), both of which produce effects that may be undesirable for a particular optical configuration.
A cube beam splitter does not normally cause a deviation in the optical path of a beam passing through it in either angle or displacement, provided that the cube beam splitter is used at normal incidence. However, a cube beam splitter tends to be a heavy component and introduces aberrations into the beam. A plate beam splitter laterally displaces the optical path of a beam, but has the advantage of introducing minimal aberrations. Two plate beam splitters can be used together in a tented configuration (as shown in FIG. 3) to correct displacement of the transmitted ray path. However, this type of assembly is relatively large and heavy.
There remains a need for a compact, lightweight beam splitting apparatus that minimizes aberration and beam deviation in both displacement and angle.